This invention relates to reader heads for optical code readers, such as bar code readers, and particularly to easily replaceable optical reader heads of relatively inexpensive construction.
It is a common necessity to replace the light source and/or light sensor components of optical code readers due to wear or malfunction. Most such replacement operations require disassembly of the code reader, removal of the element to be replaced, and soldering of the leads of the replacement element to the circuitry of the code reader.
At least one optical reader head has previously been developed which combines the light source and light sensor into a conveniently replaceable module with connectors for attachment to the code reader circuitry. This is the "Type TIL180 Bar-Code Read Head" manufactured by Texas Instruments Inc., of Dallas, Tex., which uses dual optical fibers, one of which transmits light from a light source to illuminate the codes and the other of which transmits reflected light from the codes to a light sensor. A light source designed by the same company is disclosed in Woosley U.S. Pat. No. 4,434,360, and features a light-sensing optical fiber implanted in the transparent body of the light source.
Even such modular reader heads as the TIL180, however, are not sufficiently compact to be usable in optical code readers of the highly portable type currently gaining in popularity. For example, in a copending, commonly-owned patent application of which the inventor herein is a co-inventor, Ser. No. 782,970, filed Oct. 2, 1985, now U.S. Pat. No. 4,721,849 a thin, planar, credit card-shaped optical code reader is disclosed whose shape and size demands a correspondingly thin, planar, easily replaceable reader head.
Other problems of current reader head assemblies include their high fabrication expense, necessitated by such requirements as precise alignment of optical fibers with light sensing phototransistors, and difficulties in positioning the various reader head elements reliably and accurately relative to each other.